Chain conveyor

ABSTRACT

A chain conveyor comprises a roller chain ( 6 ) [should read “8”] and a supporting rail ( 5 ) for vertically supporting the roller chain ( 6 ) [should read “8”]. The roller chain ( 6 ) [should read “8”] consists of a plurality of supporting rollers ( 3 ) that are interconnected by means of chain links ( 1 ). The chain links are of U-shaped design inasmuch as they comprise two legs ( 11, 12 ) and a base portion ( 10 ) located there between. The mean length (L) of the base portion ( 10 ) corresponds at least approximately to the distance (A) of the axes of two adjacent supporting rollers ( 3 ). The front faces of adjacent base portions of adjacent chain links are correspondingly designed and act as stops, inasmuch as they limit the mutual rotating movement of adjacent chain links, exceeding a predetermined angle, in such a way that the roller chain can transmit thrust forces. For laterally guiding the roller chain, discrete guiding elements ( 2 ) are provided which are inserted into the shafts that interconnect the chain links in an articulated manner.

FIELD OF INVENTION

The invention refers to a chain conveyor comprising a roller chain and asupporting rail for vertically supporting the roller chain. The rollerchain comprises a plurality of supporting rollers which areinterconnected by means of chain links.

The chain conveyors discussed herein are used in general in storageshelves of rack storage facilities where they serve as a conveying meansfor the goods to be stored. The conveying means is usually looped overtwo deflections to form an endless conveying means, whereby there isprovided, as the real conveying means, a conveyor chain provided withrollers. In order to save costs and weight, however, not the entirecirculating conveying means is constituted as chain, but only about halfof it, while the other half is constituted by a strap.

As a support for the goods to be stored, in most cases pallets are used.Upon storing the goods, the latter ones are laid onto the conveyor chainand, mostly by means of a fork lift truck, pushed into the storage rack.If the need arises, the goods are pulled out again by this fork lifttruck.

PRIOR ART

The document WO 94/00370 entitled “Pallet-Support Rail and Slide-inPallet-Storage Unit with Pallet-Support Rails and Pallet-Conveyor Track”discloses a chain conveyor of the generic concept discussed herein. Thisconveyor is provided with a roller chain, the supporting rollers thereofbeing connected to each other on both sides by means of a pair oflateral link plates, whereby each second link of the chain is designedas supporting strap member. The lateral link plates project downwards tosuch an extent that they can laterally guide the upper run of the rollerchain along the rail, whereby, for this purpose, the rail is smaller inits width than the mutual distance of the two link plates of a pair. Inits lower portion, the rail made of aluminum comprises a return channelin which the lower run of the roller chain is received, guided andsupported.

The problems in connection with the chain conveyor discussed aboveconsist in that the lateral link plates of the roller chain have to takeboth tractive forces as well as guiding forces. Thus, the lateral linkplates cannot be made continuously of a material which has goodself-lubricating properties, like PTFE, but they have to bemanufactured, at least partially, of a high-strength material, forexample steel. This design results in the disadvantage that thefrictional values between roller chain and guiding rail are relativelyhigh. This is also particularly true for the lower chain run received inthe return channel because here additionally the intrinsic weight of theroller chain has to be supported by the lateral link plates. Due to thehigh frictional values arising between roller chain and supporting rail,the constructional length of a chain conveyor with such a design islimited. Moreover, it has shown that the frictional resistance isadditionally increased by the tractive load of the lateral link platessimultaneously designed as guiding means.

Further problems in connection with a chain conveyor as discussed hereinbefore consist in the fact that the chains used hereby can take onlytractive forces. As soon as thrust forces act on the chain, what isalways the case upon loading of goods, the danger exists that the chainfolds by the mutual rotation of particular chain links that aresubjected to thrust forces.

Particularly that chain portion which is situated between the pallet tobe pushed in and the goods already stored is subjected to thrust forcesto a high extent. The pallet to be pushed in exerts a tractive forceonto the chain portion situated behind that pallet and guided around thefront deflection. Since such deflections have a very small diameter dueto the limited available space, they have a bad efficiency and are notsuited for high tractive forces. The tractive force in the chaindeflected around the deflection is transmitted via the elastic strap tothe rear deflection which further decreases the efficiency, whereby itis to be considered that the mass of the stored goods can amount up to20 tons.

It is understood that a folding of the chain is most undesirable underthe explained circumstances because the total length of the chain issuddenly changed by this folding; in an extreme case, this can result ina rupture of the strap and in a damage of the deflections. Moreover, bya folding of the chain, a distance between the goods, that possibly hasto be observed for the protection of the stored goods, can be changed.Also, it can happen that particularly light weight goods are raised androtated out of the horizontal position upon a folding of the chain.

A folding cannot be avoided when conventional chains are used becausethe total length of the chains and the circulating conveying means,respectively, can vary to a large extent due to for instance temperaturechanges and expansion of the strap.

OBJECTS OF THE INVENTION

Thus, it is the object of the invention to improve a chain conveyor ofthe kind referred to above such that the chain can also take andtransmit thrust forces.

A further object of the invention consists in providing a chain conveyorthat is designed with means for laterally guiding the roller chain,which are simply arranged and can be manufactured at low costs, wherebythe guide means shall present very low frictional resistances betweenroller chain and support rail.

SUMMARY OF THE INVENTION

To meet this and other objects, the present invention provides a chainconveyor comprising a roller chain and a supporting rail for verticallysupporting the roller chain. The roller chain comprises a plurality ofsupporting rollers which are interconnected by means of chain links. Thechain links are provided with stop means that limit the mutual rotatingmovement of adjacent chain links exceeding a predetermined angle suchthat the roller chain can transmit thrust forces.

By providing chain links which have stop elements that limit a mutualrotation of adjacent chain links exceeding a certain angle of rotationin such a way that the roller chain can transmit thrust forces, thedanger that particular portions of the chain are folded together iseliminated and the disadvantages connected thereto are avoided.

The chain links of the roller chain are interconnected by means of ahollow shaft member. The shaft member is designed simultaneously as asupporting axle for the supporting rollers. A discrete guiding elementis inserted into the shaft member. The guiding element that towers belowthe chain link at least at one side toward the guiding rail.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 to 3 show an individual chain link for a roller chain in threedifferent views;

FIGS. 4 to 6 show a guiding element for the roller chain in threedifferent views;

FIGS. 7 to 9 show a catch member for the roller chain in three differentviews;

FIG. 10 shows a cross section through a support rail as well as throughthe roller chain;

FIG. 11 shows a top view of a portion of a roller chain equipped withchain links according to FIGS. 1 to 3;

FIG. 12 shows a portion of the roller chain according to FIG. 11 in aside view.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

The FIGS. 1 to 3 show a chain link 1 for a roller chain in a sideelevation, a front elevation and a top elevation. The chain link 1 isdesigned essentially U-shaped and comprises a base portion 10 as well astwo legs 11, 12. The base portion situated between the two legs 11, 12constitutes the top cover of the chain link 1. Both legs 11, 12 of thechain link 1 are provided with bores 13 which serve for receiving ineach case a shaft for interconnecting the chain links 1 and for bearingand supporting a support roller.

The base portion 10 of the chain link 1 is provided with two recesses 16arranged along one of the legs 11 and having a width b that is greaterthan the wall thickness of a leg 11, 12. By providing these recesses 16,the assembling of several uniformly designed chain links 1 to a chain isfavored inasmuch as one leg 11, 12 of a preceding or subsequent chainlink 1, in each case rotated by 180° around the height axis, whichextends vertically through the center of base portion of each chain linkengages such a recess 16.

Moreover, the base portion 10 is provided with a slot 15 runningcrosswise to its longitudinal axis. This slot serves for receiving acatch member made of an elastic material, as will be further explainedherein below with the help of FIGS. 7 to 9.

The basic shape of such a chain link 1 is manufactured preferably bypunching, while the U-shaped design is created by a subsequent bendingof the punched out part.

The two end portions 17, 18 of the base portion 10 of a chain link 1 arepreferably of oblique shape. On the other hand, the two end portions ofthe base portion can be provided with a stepping, as outlined by thebroken lines L.

The one leg 12 is provided with two projections 14 towering above thetop side of the base portion 10, whereby, due to manufacturing reasons,in each case the leg 12 adjacent to the shorter portion 17 a, 18 a ofthe base portion 10 comprises such projections 14.

In the FIGS. 4 to 6, a guiding element 2 for the roller chain is shownin three different views. This guiding element 2 essentially consists ofa guiding plate 21 as well as of a clamping part 24. Integrally formedat the inner side of the guiding plate 21, there is provided a stripmember 23. The lower portion 26 of the guiding plate 21 serves forlaterally guiding the roller chain, while the guiding plate comprises arest surface provided at its top side and is designed to support thelower chain run of a circulating chain. The mode of operation of thisguiding plate 21 will be further explained herein below with the help ofFIG. 10.

The FIGS. 7 to 9 show the catch member 19 in a side elevation, a frontelevation and a top elevation. The catch member 19, preferablymanufactured of rubber, serves as a rest for goods to be supported bythe chain links. For fixing it in the slot machined into the baseportion of the chain link, the catch member 19 comprises a holdingportion 20 which is correspondingly designed to engage the slot. Forfixing, the catch member 19 in the slot 15 the holding portion 20 isslid through the slot and, thereafter, the catch member is rotated by90°. The catch member 19 preferably slightly towers above theprojections of the chain link such that light goods do not rest on theprojections, but on the catch member. However, by the elastic design ofthe catch member 19, it is ensured that heavy goods compress the catchmember and, thereby rest against the projections, whereby a safe,non-positive connection between chain link and goods to be stored or thepallet upon which the goods are stored is ensured.

FIG. 10 shows a cross section through a support rail 5 as well as aroller chain 8. The support rail 5 comprises, at its top side, a tracksurface 6 projecting upwards that is laterally defined by two guidefaces 31, 32. At the bottom side, the support rail 5 is provided with ahollow chamber H having an open bottom in which are provided twoauxiliary rails 7 on which the guiding plates 21 of the guiding elements2 rest with their rest surfaces 25 and on which the lower run 8 b of thechain is vertically supported.

The roller chain 8 is constituted by a plurality of chain links 1designed according to FIGS. 1 to 3 and by supporting rollers 3, wherebyin each case two chain links are interconnected by a shaft 28 in anarticulated manner. The shafts 28 simultaneously serve for bearing thesupporting rollers 3. Into the particular shaft 28, a guiding element 2is inserted which towers below the chain link 1 at one side. At theother side, the clamping part 24 of the guiding element 2 engages theleg 12 a whereby both the shaft 28 as well as the guiding element 2 canbe fixed in the position shown here. Additionally, for securing theguiding element 2, a safety pin 29 can be provided, as illustrated,which is anchored in a self-locking manner. In order to form a chain ofuniform chain links 1, these are arranged alternately rotated by 180°around their height axis, whereby the one chain link is offset withregard to the other chain link, as seen in longitudinal direction of theroller chain, by an amount corresponding to the wall thickness of a legof a chain link. Besides the chain links 1, also the guiding elements 2are arranged alternately rotated by 180°; this means, in other words,the guiding elements 2 are inserted into the particular shaft 28alternately once from the left side and once from the right side, suchthat the roller chain 8 is guided on both sides of the track surface 6.The strip member 23 of the guiding element 2 extends along the bottomside of the particular leg of a chain link and prevents the guidingelement 2 from being rotated, whereby the length of the strip member 23approximately corresponds to the wall thickness of a leg of a chainlink. It is to add that the roller chain 8 constitutes onlyapproximately 60% of the circulating conveying means, while theremaining 40% consist of a strap that is fixed to the two ends of thechain.

FIG. 11 shows a top view of a portion of a roller chain that is providedwith uniform chain links 1 according to FIGS. 1 to 3 as well as withguiding elements 2 according to FIGS. 4 to 6. It can be seen from thisillustration that the chain links 1 a, 1 b, 1 c, 1 d are arrangedalternately rotated around the height axis by 180° and that the onechain link is offset with regard to the other chain link 1 a, 1 b, 1 c 1d, as seen in the longitudinal direction of the roller chain 8, by anamount of the wall thickness of the leg of a chain link 1 a, 1 b, 1 c, 1d, such that in each case the one leg 11, 12 of a chain link engages therecess 16 (FIG. 3) in the base portion of the adjacent chain link. Thisdesign allows that the chain links 1 a, 1 b, 1 c, 1 d, also can take upand transmit lateral forces.

Moreover, it is evident that the mean length L of the base portion 10 atleast approximately corresponds to the distance A of the axes of twoadjacent supporting rollers 3. The base portion 10 preferably is shorterthan the distance of the axes of two adjacent supporting rollers byapproximately 0.5 to 3 mm, such that, the chain being in its stretchedstate, also creates a gap b2 in the order of 0.5 to 3 mm between thefront faces of adjacent base portions 10 b, 10 c of adjacent chain links1 b, 1 c. This design has the effect that the mutual rotational movementof adjacent chain links with respect to one another, exceeding a certainangle of rotation, is limited due to the fact that the front faces ofadjacent base portions abut against each other turning back the chainlinks. In this connection, it is important that the front faces ofadjacent base portions of adjacent chain links are designed tocorrespond with one another. A roller link designed in such a way, thus,can transmit thrust forces, without the danger that the chain foldstogether at certain portions.

FIG. 12 shows the portion of the roller chain according to FIG. 11 in aside view. In this illustration, the alternatingly arranged guidingelements 2 can be seen towering below the chain links.

A chain conveyor designed in such a way is of very simple constructionand can be manufactured at low costs, because both the chain links aswell as the guiding elements are of uniform design. By the provision ofstop members limiting the mutual rotating movement of adjacent chainlinks exceeding a predetermined angle in the above explained manner, theroller chain can also transmit thrust forces.

What is claimed is:
 1. A conveyor mechanism for use in rack storagefacilities, the conveyor mechanism supporting articles placed thereonand moving when the articles on the conveyor mechanism are pushed by athrust force, said conveyor mechanism comprising: a plurality of chainlinks, each having a surface on which an article may be placed, adjacentchain links being interconnected to move together, rollers beingconnected with said chain links and being movable with said chain links,and a supporting rail for vertically supporting said rollers and saidchain links, said rollers moving along said rail when said chain linksmove, each of said chain links having a stop element which engages astop element on an adjacent chain link to limit mutual rotating movementof the adjacent chain links so that the thrust force applied on thearticle is transmitted from a chain link supporting the article to theother chain links and to said rollers so that said chain links and saidrollers move along said rail; each of said chain links being U-shaped,the U-shape including two legs and a base portion located between saidtwo legs, the mean length of the base portion at least approximatelyequaling the distance between axles of two adjacent rollers, andadjacent faces of the base portions of adjacent chain links being ofcomplementary design and acting as said stop elements.
 2. The conveyormechanism as in claim 1 wherein a gap of less than 5% of the length of achain link exists between said front faces of adjacent chain links whensaid conveyor mechanism is in a stretched state.
 3. The conveyormechanism as in claim 1 wherein said base portion of said chain links isan upper cover for said conveyor mechanism and protects said rollers andsaid rail from contamination.
 4. The conveyor mechanism as in claim 1wherein two end portions of said base portion of a chain link comprisesa stepping design.
 5. The conveyor mechanism as in claim 1 wherein twoend portions of said base portion of a chain link comprises an obliquedesign.
 6. The conveyor mechanism as in claim 1 wherein a leg adjacent ashorter portion of said base portion includes a projection that extendsabove said base portion.
 7. The conveyor mechanism as in claim 1 whereinsaid base portion includes two recesses arranged along one leg andhaving a width that is greater than a wall thickness of a correspondingleg on an adjacent chain link.
 8. The conveyor mechanism as in claim 1wherein adjacent chain links of said conveyor mechanism are alternatelyrotated about their height axis 180 degrees and whereby adjacent chainlinks are offset along a longitudinal direction by a distance equal to athickness of a wall of a leg of a chain link.
 9. The conveyor mechanismas in claim 1 wherein said chain links are interconnected by means of ashaft designed as a supporting axle for the supporting rollers.
 10. Theconveyor mechanism as in claim 1 wherein said base portion is providedwith a slot running transverse to a direction of movement of saidconveyor mechanism.
 11. The conveyor mechanism as in claim 10 wherein acatch member having a holding portion is insertable into said slot insaid base portion of said chain link and upon a rotation of 90 degreesbecomes fixed to said base portion.
 12. A conveyor mechanism for use inrack storage facilities, the conveyor mechanism supporting articlesplaced thereon and moving when the articles on the conveyor mechanismare pushed by a thrust force, said conveyor mechanism comprising: aplurality of chain links, each having a surface on which an article maybe placed, adjacent chain links being interconnected to move together,rollers being connected with said chain links and being movable withsaid chain links, a supporting rail for vertically supporting saidrollers and said chain links, said rollers moving along said rail whensaid chain links move, each of said chain links having a stop elementwhich engages a stop element on an adjacent chain link to limit mutualrotating movement of the adjacent chain links so that the thrust forceapplied on the article is transmitted from a chain link supporting thearticle to the other chain links and to said rollers so that said chainlinks and said rollers move along said rail; said chain links beinginterconnected by means of a shaft designed as a supporting axle for thesupporting rollers; and a discrete guiding element being insertable intosaid shaft, said guiding element having a guide plate that towers belowthe chain at least at one side toward said rail.
 13. The conveyormechanism as in claim 12 wherein said guiding element is provided with astrip member, said strip member being directed toward a chain link andextending along a lower side of a leg of said chain link, a length ofsaid strip member corresponding to a maximum thickness of a wall of aleg of said chain link.
 14. The conveyor mechanism as in claim 12wherein said rail comprises a track surface at a top side of said rail,said track surface being laterally defined by two guiding faces.
 15. Theconveyor mechanism as in claim 14 wherein each guiding element includesat least one guiding member which is adapted to cooperate with saidguiding faces.
 16. The conveyor mechanism as in claim 14 wherein saidguiding elements are made of a plastic material having self-lubricatingproperties.